Idling @ 8000 rpm

[Katman]

Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.

[cbfb]

I've only got a 16-29mm dia one My toolbox with all my bits and bobs isn't here at home.

Ah well no worries, thanks for looking.

Must say I was a bit disappointed with Freedom Suzuki (who have otherwise been generally great in the past if a bit pricey), not much help there. City Honda (who couldn't help) led me on a bit of a wild goose chase (although they had the right intentions) by giving me the wrong directions to Manawatu Motorcycles; turns out it was nowhere near where they said, so didn't get there today. Anza did their best but nothing doing, although they said ring back if I really struggle and they would dig around.

Who would have thought it would be this bloody hard!!!

Anyway if anyone's interested in where to find stainless hose clamps:
Ullrich Aluminium - dealt with these guys before, very helpful
HCD Flowtech
Steve's Marine

So good news is I can get one, bad news is not before the long weekend

[cbfb]

Get the hammer.

Tried that, bashed me thumb

Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.

Unfortunately I've pulled the carbs off now so can't tell if this was the issue. But having said that will definitely watch out for that when I'm putting everything back together, cheers.

[jonbuoy]

Exposing (and covering) the inlet/s may not be helpful. CV carbs do not behave right without the still air of an attached airbox to draw on.

Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.

[MSTRS:Me]

Check the positioning of the manifold clamps. Sometimes the screw piece can foul with the throttle actuator possibly stopping it returning to the idle screw.

Good point. Idling at 8000 suggests a bit more than just the mixture being out of whack.

Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.

You'd be surprised.

[cbfb]

Its idling in the driveway - don´t think moving air turbulence will be too much of an issue to prove an 8000 RPM idle problem.

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

[jonbuoy]

Yes it does have an effect but at standstill/idle its marginal, your not fine tuning the mixture or adjusting the carb balances - your engines revving its tits off with a closed throttle. It was a suggestion to prove which if any of the carbs are causing the fault. Pod filters, airbox, velocity stacks pair of nylon tights - whatever is on the carb mouth - the engine shouldn't be "idling" at 8000 RPM. Plenty of cars run with pod filters/velocity stacks on CV carbs. Theorising on the interweb and wishing it isn´t the part you´ve already stripped down three times causing the problem won´t fix it.

[MSTRS:Me]

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

Probably CV type.
I may not have this quite right, but all carbs operate by way of a vacuum. Disturbing the 'constant' vacuum upsets their performance. But since CV carbs rely on that vacuum to lift the slide/needle as well, it is critical that airflow/vacuum is just right.

[jonbuoy]

Good point. Idling at 8000 suggests a bit more than just the mixture being out of whack.


You'd be surprised.

No I wouldn´t - I would however be very surprised if I took the airbox/filter off and the engine revved to 8,000 RPM. Maybe a rise of 250-500 RPM not 7,000 RPM

[jonbuoy]

I'd always thought that the air filter was necessary to regulate the air getting into the carbs even at standstill? I seem to remember a few engines I've played with that didn't run right with no filter on. Not something I usually do reguarly for obvious reasons.

Airfilter stops dirt getting into the engine, nothing more. It will run better without an airfilter (if the mixture is adjusted), your engine won´t last long sucking in dirt and crap off the road.

[cbfb]

Yes it does have an effect but at standstill/idle its marginal, your not fine tuning the mixture or adjusting the carb balances - your engines revving its tits off with a closed throttle. It was a suggestion to prove which if any of the carbs are causing the fault. Pod filters, airbox, velocity stacks pair of nylon tights - whatever is on the carb mouth - the engine shouldn't be "idling" at 8000 RPM. Plenty of cars run with pod filters/velocity stacks on CV carbs. Theorising on the interweb and wishing it isn´t the part you´ve already stripped down three times causing the problem won´t fix it.

Ah OK, cheers for the explanation.

[MSTRS:Me]

No I wouldn´t - I would however be very surprised if I took the airbox/filter off and the engine revved to 8,000 RPM. Maybe a rise of 250-500 RPM not 7,000 RPM

Diagnosing the problem wouldn't necessarily be helped by removing the airbox. In saying that, if the inlets are exposed, then at least one could see if the slides were all level with each other.
An air leak around the manifold on one, or even all, of the carbs doesn't explain 'idling' at 8000rpm.
I think KM is on to it, with his suggestion of something interferring with the butterflies.

[cbfb]

Diagnosing the problem wouldn't necessarily be helped by removing the airbox. In saying that, if the inlets are exposed, then at least one could see if the slides were all level with each other.
An air leak around the manifold on one, or even all, of the carbs doesn't explain 'idling' at 8000rpm.
I think KM is on to it, with his suggestion of something interferring with the butterflies.

Have checked that the slides are all returning to bottom, not checked what they are doing when the engine's running though.

Bit of a bugger if the manifold seal doesn't explain it, was hoping the new hose clamp would fix it.

Well hopefully KM IS right then (Edit: of course KM is right, could well be caused by that - I mean I hope that is what the problem was), will check very carefully that nothing is jamming open the throttles, but I am pretty certain it was OK before, we will see!

[MSTRS:Me]

If you re-install everything, then before your fire her up, see how much play there is at the grip. There should be a small amount anyway, but it should be easy to ascertain whether it is excessive. If there is a lot of play, chances are those butterflies are somewhat open. Which would explain everything.
Of course, then you'd have to figure out just what is holding them open.
One thing at a time...

[cbfb]

If you re-install everything, then before your fire her up, see how much play there is at the grip. There should be a small amount anyway, but it should be easy to ascertain whether it is excessive. If there is a lot of play, chances are those butterflies are somewhat open. Which would explain everything.
Of course, then you'd have to figure out just what is holding them open.
One thing at a time...

There is quite a bit of play at the grip, problem is I had the bike apart so the throttle adjustment has changed. However I have checked that the butterflies are fully closed with the throttle shut, which they are. Is this what you mean?